85 Questions
What is the main role of glycolipids in the cell membrane?
Maintain stability and facilitate cellular recognition
Which enzymes are produced by pathogenic bacteria to dissolve cell membranes?
Phospholipases
Which molecule is a component of glycosphingolipids but not phospholipids?
Ceramide
What is attached to the amino alcohol sphingosine in glycosphingolipids?
Fatty acid unit
Which of the following is NOT a subclass of glycolipids?
Phosphatidylcholine
What is the main outcome of attaching different polar head groups to diacylglycerol?
Degradation by phospholipases
What type of molecule is a phospholipid?
Amphipathic
Which of the following is a molecule with high physiological and metabolic relevance?
Diacylglycerol
Which lipid serves as the building blocks of other lipids?
Glycerophospholipids
What type of fatty acids are SFA and UFA?
Saturated and unsaturated
Which category includes prostaglandins, thromboxanes, and leukotrienes?
Eicosanoids
What is the precursor for all classes of steroid hormones?
Cholesterol
Why do steroid hormones need to be attached to plasma proteins for transportation in the blood?
Due to hydrophobicity
Which lipoprotein functions to keep its component lipids soluble for transport in plasma?
High-density lipoproteins (HDL)
Where do abnormalities in lipoprotein metabolism generally occur?
At the site of lipid utilization
Which type of lipoprotein has the highest density?
High-density lipoproteins (HDL)
What is the function of plasma lipoproteins?
To provide a mechanism for lipid transport in plasma
What is the main source of essential fatty acids that must be obtained from the diet?
Fish oils
Which fatty acid is the precursor of arachidonic acid, which is important for eicosanoid synthesis?
Linoleic acid
In phospholipids, what type of group links the polar head and nonpolar fatty acid tails?
Phosphate group
Why are phospholipids considered amphipathic in nature?
They have both hydrophilic and hydrophobic components
Which part of a phospholipid molecule points outward to the aqueous environment in cell membranes?
Hydrophilic head
Apart from being main components of cell membranes, where else can nonmembrane phospholipids be found?
In lung surfactants
What is the physiological relevance of cardiolipin?
Maintenance of electron transport chain complexes
Which function is NOT associated with platelet-activating factor (PAF)?
Enhances erythrocyte production
Where does the synthesis of glycerophospholipids primarily occur?
Smooth Endoplasmic Reticulum (sER)
Which process results in the conversion of phosphatidic acid to diacylglycerol?
Phosphatase action
In phospholipid biosynthesis, what is the precursor molecule for glycerophospholipids?
Fatty acyl CoA
Which organelle is responsible for modifying newly synthesized phospholipids before they compose cell membranes?
Golgi Apparatus
What type of fatty acids are the building blocks of lipids?
Saturated and unsaturated fatty acids
Which lipid molecule is a combination of a fatty acid with an alcohol such as glycerol?
Neutral fats
In glycerophospholipids, what is the primary role of the glycerol backbone?
Linking the polar head to the nonpolar fatty acid tails
What is the main function of triacylglycerols (TAG) in cells?
Provide energy during fasting periods
In what form are fatty acids mainly circulating in the blood plasma?
Esterified forms within lipoprotein particles
Why do long-chain-length fatty acids (LCFA) require association with proteins for blood plasma circulation?
To increase their solubility in water
What effect does the presence of double bonds have on the melting temperature (Tm) of fatty acids?
Decreases the Tm
Which aspect of fatty acid structure gives them an amphipathic nature?
Anionic group
What structural characteristic defines saturated fatty acids?
Absence of double bonds
What is the main function of cholesteryl esters (CE) in the body?
Modulate the fluidity of lipoproteins
Why are cholesteryl esters (CE) not found in cell membranes?
They are only present in low levels associated with lipoproteins
What role does the liver play in cholesterol homeostasis in the body?
It controls the delicate balance of cholesterol levels in the body
How does cholesterol contribute to the formation of dangerous plaque formations?
Due to disturbances in the balance controlled by the liver
Which statement accurately describes cholesterol's role as a sterol?
Cholesterol acts as a precursor for eicosanoid synthesis
In what form do most plasma cholesterol exist for transport?
Cholesteryl esters with fatty acids attached
What is the role of cardiolipin in the cell?
Maintains electron transport chain complexes
Where does the synthesis of glycerophospholipids primarily occur?
Endoplasmic reticulum
What is the function of platelet-activating factor (PAF) in the body?
Activates inflammatory cells
What role does the smooth endoplasmic reticulum (sER) play in phospholipid synthesis?
Produces phospholipids from precursors
What is the precursor molecule for glycerophospholipids in phospholipid biosynthesis?
Fatty acyl CoA
Which organelle is responsible for modifying newly synthesized phospholipids before they become part of cell membranes?
Golgi apparatus
Why must steroid hormones be attached to plasma proteins for transportation in the blood?
To enhance their solubility due to their hydrophobic nature
Which lipoprotein has the highest density among the listed types?
High-density lipoproteins (HDL)
Where do abnormalities in lipoprotein metabolism generally occur?
At the site of lipoprotein production
What is the main function of plasma lipoproteins?
To keep their component lipids soluble for transport in plasma
In what way do chylomicrons, VLDL, LDL, and HDL differ from each other?
Lipid and protein composition, size, density, and site of origin
What is the precursor for all classes of steroid hormones?
Cholesterol
What is the main component of lecithin?
Phosphatidylcholine
Which type of phospholipid is an important component of the myelin sheath of nerve fibers?
Sphingomyelin
What is the precursor molecule of phosphatidylinositol?
Inositol
Which alcohol group is involved in the synthesis of Phosphatidylethanolamine?
Ethanolamine
What is the main outcome of attaching serine to phosphatidic acid?
Formation of Phosphatidylserine
Which phospholipid is essential for regulating intracellular signaling, lipid transportation, and vesicular trafficking?
Phosphatidylinositol
What is the physiological relevance of cardiolipin in the cell?
Maintains electron transport chain complexes
Where does the synthesis of phospholipids primarily occur?
Smooth endoplasmic reticulum (sER)
Which organelle is responsible for modifying newly synthesized phospholipids before they become part of cell membranes?
Golgi apparatus
What is the precursor molecule for glycerophospholipids in phospholipid biosynthesis?
Glycerol-3-phosphate
What is the primary role of platelet-activating factor (PAF) in the body?
Induces hypersensitivity reactions
How are glycerophospholipids synthesized?
$2$ fatty acids linked to coenzyme A are joined to glycerol-3-phosphate.
What is the term used to describe fatty acids with 13-21 carbons?
Long-chain fatty acids (LCFA)
Which carbon atom in a fatty acid is referred to as the α-carbon?
Carbon 2
What is the reference point used to name double bonds in a fatty acid?
ω-carbon
Arachidonic acid is categorized as an ω-6 fatty acid because:
The first double bond is six carbons from the ω end
What is the term used to describe fatty acids with fewer than 5 carbons?
Short-chain fatty acids (SCFA)
What is the function of glycosphingolipids located in the outer parts of the plasma membrane?
Antigenic/recognition function
Which blood group antigen is associated with the presence of GalNAc as the terminal sugar on the glycan?
A
What is the main source of arachidonic acid, the immediate precursor of eicosanoids?
Membrane phospholipids
Which lipid derivatives are classified as local hormones due to their acting locally and not being stored?
Prostaglandins, thromboxanes, and leukotrienes
Which lipid molecule serves as a mediator of allergic response and inflammation?
Leukotrienes
What is the essential characteristic that distinguishes arachidonic acid from essential fatty acids?
Not stored in tissues
What is the structure of cholesterol consisting of?
Four fused hydrocarbon rings
Where are cholesteryl esters (CE) primarily found in the body?
Associated with lipoproteins
Which molecule is an essential precursor for the synthesis of steroid hormones?
Cholesterol
What is the primary source of cholesterol entry into the liver for maintaining homeostasis?
Dietary intake and de novo synthesis
What crucial function does cholesterol perform in cell membranes?
Enhancing membrane fluidity
In what form is most plasma cholesterol found for transport?
Cholesterol esterified with fatty acids
Test your knowledge on the physiological and metabolic relevance of lipids including saturated and unsaturated fatty acids, glycerides, neutral fats, phospholipids, glycolipids, and lipoproteins. Explore the different types of lipids and their roles in the body's functions.
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